Nuclear Reactor Primary Circuit Sleeve Design for Thermal Stress Reduction
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Solution Overview
Problem
The existing nuclear reactor primary circuits face significant thermal stress and fatigue issues at the tapping points of ancillary piping due to temperature differences, leading to a risk of leakage or rupture.
Innovation Solution
A primary circuit design where the sleeve's free peripheral edge has upstream and downstream sectors with varying depths of penetration, a beveled or crenellated profile, and a constriction to manage fluid mixing and reduce thermal stress, along with a convergent section to enhance mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the ancillary piping is tapped on the cold leg of the primary circuit to inject liquid loads, then the volume and chemistry of primary liquid can be adjusted, but significant thermal fluctuations cause fatigue and increase the risk of leakage or rupture at the tapping
Solution Approach 1:
A sleeve is introduced as an intermediary component between the ancillary piping and the primary piping. The sleeve extends into the interior volume of the primary piping and deflects hot primary liquid vortices away from the mixing zone, reducing thermal fluctuations at the tapping connection and thereby preventing fatigue and leakage while maintaining the ability to inject liquid loads
2Device complexity
If the sleeve stops flush with or slightly set back from the primary pipe, then the structure is simple, but thermal stresses from temperature differences between mixing fluids cause fatigue and leakage risk
Solution Approach 1:
The sleeve is extended in the radial dimension into the interior volume of the primary piping by a distance greater than the radius of the ancillary piping. This dimensional extension allows the sleeve to intercept and deflect hot primary liquid vortices before they reach the mixing zone, reducing thermal stresses without significantly increasing structural complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces the risk of fatigue and leakage by deflecting hot primary liquid vortices and moving the mixing zone away from critical areas, thereby minimizing thermal and mechanical stresses, and increasing the mechanical strength of the connection.
Implementation Method 1
the end of the sleeve is delimited by a free peripheral edge having at least upstream and downstream sectors facing respectively upstream and downstream of the primary piping, the upstream sector penetrating deeper into the interior volume from the primary piping than the downstream sector
Implementation Method 2
the constriction extends between a restriction formed in the sleeve and the second free end, the restriction being provided in the connection zone of the sleeve on the auxiliary pipe
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a nuclear reactor primary circuit comprising a primary pipeline (30), which defines an internal volume (32) and in which a primary nuclear reactor coolant downwardly runs, an additional pipeline (26) which is branched to the primary pipeline (30) and defines an internal volume communicating with the internal volume (32) of the primary pipeline (30) and a cuff (36) whose first end (50) is connected to the additional pipeline (26) and the second free end (52) is positioned in the internal volume (32) of the primary pipeline (30). According to said invention, the second end (52) is delimited by a free peripherial edge (53) comprising at least one upstream and downstream sections (56, 58) which are oriented towards the upstream, wherein the upstream section (56) penetrates into the internal volume (32) deeper from the primary pipeline (30) than the downstream section (58).